Effects of High-Intensity Interval Training Protocols on Blood Lactate Levels and Cognition in Healthy Adults: Systematic Review and Meta-Regression

The effect of ischemic preconditioning on physical fitness and performance: a meta-analysis in healthy adults

PURPOSE

This meta-analysis aims to assess the impact of ischemic preconditioning (IPC) on physical fitness and performance, with a focus on its specific role in aerobic endurance, anaerobic endurance, explosive power and strength.

METHODS

Systematic searches were conducted across multiple databases (CNKI, CBM, Cochrane Library, Web of Science, PubMed, and Embase) up to September 6, 2023. We included studies that employed randomized controlled trial methods and sham ischemic preconditioning as the placebo group, and two reviewers independently screened literature and extracted data, using Review Manager 5.3 for analysis.

RESULTS

This meta-analysis comprises 27 articles with 405 individuals, selected according to specified criteria. IPC significantly increased the blood lactate concentration after anaerobic speed endurance exercise (MD = 0.74, P = 0.03), the blood lactate concentration after incremental exercise (MD = 0.49, P = 0.04), the blood lactate concentration after muscular endurance exercise (MD = 0.68, P = 0.02), and the one-repetition maximum (MD = 1.38, P = 0.00001). Furthermore, it also significantly shortened completion time of the exercises primarily powered by glycolysis (MD =  - 0.49, P = 0.01) and completion time of the exercises primarily powered by aerobic system (MD =  - 7.27, P = 0.05), while marginally prolonging time to exhaustion (MD = 22.68, P = 0.08). However, IPC had no significant effect on maximum oxygen uptake, blood lactate concentration in fixed-load aerobic endurance exercise, peak power, or peak aerobic power, nor on completion time of the exercises primarily powered by phosphagen system.

CONCLUSION

IPC could serve as a method to enhance physical performance, particularly for exercises primarily powered by aerobic system and glycolysis. Future research might explore how various cycles, locations, and widths of IPC affect the physical performance of participants with different activity levels.

Acute effects of high-intensity interval training and moderate-intensity continuous training on executive functions in healthy older adults

Numerous studies have demonstrated that executive functions benefit from high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT). However, the immediate effects of HIIT and MICT on these functions in older adults have not been compared. This study aimed to examine the acute impact of HIIT and MICT on executive function components in this demographic. Twenty-five healthy community-dwelling older adults (15 females; average age 67.1 ± 4.5 years) participated. The study involved three sessions: an initial session with cognitive assessments (Stroop Task: Naming, Inhibition, and Switching) and a maximal continuous graded exercise test, followed by two sessions involving HIIT (15s at 100% peak power output, 15s rest, 2 × 20 min) or MICT (34 min at 60% peak power output) training protocols in random order. Cognitive tests were administered immediately after and 45 min post-training. The results showed a significant difference in Switching reaction times between MICT and HIIT, with HIIT showing a greater reduction in Switching times after 45 min (p = 0.019). In conclusion, our study indicates that HIIT's beneficial effects on executive functions demonstrated a larger effect size than those of MICT. This suggests that brief, high-intensity exercise could be more effective in enhancing executive functions among older adults.

Optimal intensity and type of lower limb aerobic training for patients with chronic obstructive pulmonary disease: a systematic review and network meta-analysis of RCTs

BACKGROUND

Lower limb aerobic exercise is the core component of pulmonary rehabilitation for chronic obstructive pulmonary disease (COPD) patients. The optimal intensity and type (e.g., interval or continuous) of exercise training remains to be determined.

OBJECTIVES

We aimed to evaluate the optimal intensities and types of lower limb aerobic exercise in patients with COPD.

DESIGN

Systematic review and network meta-analysis of randomized controlled trials.

DATA SOURCES AND METHODS

The PubMed, Web of Science, Embase, and the Cochrane Central Register of Controlled Trials were searched for relevant data. The interventions were classified according to their intensity and type as high-intensity interval training (HIIT), high-intensity continuous training (HICT), moderate-intensity continuous training (MICT), and low-intensity continuous training (LICT). We assessed exercise capacity using peak work rate (Wpeak) and the 6-min walking test (6-MWT). Lung function was evaluated by measuring peak minute ventilation (VE) and the percentage of predicted FEV1 (FEV1pred%). Dyspnea was assessed using the Modified Medical Research Council (mMRC) scale. Quality of life was measured with the Chronic Respiratory Questionnaire (CRQ).

RESULTS

Fifteen studies were identified (979 subjects). HIIT showed the greatest improvement in Wpeak, 6-MWT, VE, and mMRC compared to usual care (MD 18.48 (95% CI 12.35, 24.60), 67.73 (34.89, 100.57), 6.26 (2.81, 9.72), and -0.53 (-0.89, -0.17), respectively) and showed the improvement in CRQ (MD 10.80 (95% CI 1.65, 19.95)). MICT showed improvement in Wpeak and 6-MWT (MD 18.28 (95% CI 11.20, 25.22), 61.92 (28.34, 95.51)) similar to HICT (MD 16.08 (95% CI 8.19, 23.84), 64.64 (28.70, 100.57)) and showed the highest improvement in CRQ compared to usual care (MD 10.83 (95% CI 1.68, 19.98)). LICT significantly improved Wpeak compared to usual care (MD 13.47 (95% CI 4.77, 22.13)). The quality of evidence for outcomes varied from very low to moderate.

CONCLUSION

HIIT and MICT might be optimal training approaches for patients with COPD. LICT exhibited limited clinical efficacy. While HICT was as effective as MICT, it caused more dyspnea.

TRIAL REGISTRATION

This systematic review and network meta-analysis was prospectively registered with PROSPERO (No. CRD 42024520134).

Effects of increasing fitness through exercise training on language comprehension in monolingual and bilingual older adults: a randomized controlled trial

Exercise training has been proposed to counteract age-related cognitive decline through improvements in cardiorespiratory fitness (CRF hypothesis). Research has focused on cognitive domains like attention and processing speed, and one cross-sectional study reported a positive relationship between CRF and language production in older adults. In a randomized controlled trial, we investigated whether these benefits could extend to language comprehension in healthy older adults, and whether bilinguals, for whom language processing is more costly, would exhibit greater benefits than monolinguals. Eighty older English monolinguals and 80 older Norwegian-English bilinguals were randomized into either a 6-month exercise training group or into a passive control group. We assessed CRF (VO2peak) and language comprehension (reaction times to spoken word monitoring) in first (L1, all participants) and second language (L2, bilinguals only), before and after the intervention. We found that monolinguals in the exercise group (compared to the control group) were faster in comprehension following the intervention. Moreover, this effect was mediated by exercise-induced increases in VO2peak, supporting the CRF hypothesis. This extends previous cross-sectional research and establishes a causal link between exercise training and speeded comprehension in older monolinguals. However, despite inducing increased VO2peak, exercise training did not affect bilingual (L1 or L2) comprehension, and bilinguals in both groups were slower after the intervention period. Exploratory analyses suggested that this slowing may be driven by participants with low L2 proficiency, but further research is needed to examine whether bilingual language processing is in fact unaffected by exercise training and its consequent improvements in CRF.

Advanced Wearable Devices for Monitoring Sweat Biochemical Markers in Athletic Performance: A Comprehensive Review

Wearable technology has advanced significantly, offering real-time monitoring of athletes' physiological parameters and optimizing training and recovery strategies. Recent developments focus on biosensor devices capable of monitoring biochemical parameters in addition to physiological ones. These devices employ noninvasive methods such as sweat analysis, which reveals critical biomarkers like glucose, lactate, electrolytes, pH, and cortisol. These biomarkers provide valuable insights into an athlete's energy use, hydration status, muscle function, and stress levels. Current technologies utilize both electrochemical and colorimetric methods for sweat analysis, with electrochemical methods providing higher precision despite potential signal interference. Wearable devices such as epidermal patches, temporary tattoos, and fabric-based sensors are preferred for their flexibility and unobtrusive nature compared to more rigid conventional wearables. Such devices leverage advanced materials and transmit real-time data to computers, tablets, or smartphones. These data would aid coaches and sports medical personnel in monitoring athletes' health, optimizing diets, and developing training plans to enhance performance and reduce injuries.

Comparing the effect of high-intensity interval exercise and voluntary exercise training on cognitive functions in rats

It is known that exercise increases brain-derived neurotrophic factor (BDNF) levels in the hippocampus, the brain region responsible for learning and memory, resulting in improved cognitive functions and learning processes. However, it is claimed that different types of exercise cause different responses in the brain. It is thought that lactate and osteocalcin secreted in response to exercise are associated with an increase in BDNF levels. However, there are not enough studies on this subject. This study aimed to compare the effects of high-intensity interval training (HIIT) and voluntary exercise training on cognitive performance and molecular connections. Male rats were randomly divided into control, voluntary exercise training and HIIT groups. The voluntary exercise group had free access to the voluntary wheel for 8 weeks. The HIIT group performed HIIT on the treadmill 3 days a week for 8 weeks. The rats underwent open field (OF), elevated plus maze (EPM) and Morris water maze (MWM) tests 24 h after the last exercise training. Then, after blood was drawn under anesthesia, the rats were sacrificed and their hippocampus tissues were separated. Glucocorticoid and BDNF levels in the blood were evaluated by enzyme-linked immunosorbent assay (ELISA), and osteocalcin and BDNF expressions in the hippocampus were evaluated by real-time quantitative reverse transcription-polymerase chain reaction (RT-PCR). Neither voluntary exercise training nor HIIT had any significant effect on behavioral parameters assessed by OF, EPM and MWM tests. However, BDNF expression in hippocampus tissue was higher in the HIIT group than in the control group. In addition, osteocalcin expression in hippocampus tissue was higher in the HIIT and voluntary exercise groups than in the control group. In conclusion, according to the findings we obtained from this study, although it does not have a significant effect on cognitive functions, the effect of HIIT on brain functions seems to be more effective than voluntary exercise.

Intensity of Physical Activity in Young People: Focus on Emotional, Cognitive, and Healthy Lifestyle-Related Variables

The college years represent a crucial developmental period in which unhealthy behaviors, including smoking, alcohol consumption, inadequate physical activity (PA), poor sleep quality, and unhealthy nutrition habits are often acquired, influencing the onset or exacerbation of pre-existing mental disturbances such as anxiety, depression, or difficulties in emotion regulation. Our aim was to analyze the effect of the intensity of physical activity (PA) on the emotional, behavioral, and cognitive variables in a sample of young people. We recruited 103 participants (19.85 ± 0.25) who completed several online questionnaires (IPAQ-SF, STAI-t, DERS, UPPS-P, ISP-20, and Mini-IPIP). Subsequently, face-to-face sessions were conducted to assess the cognitive variables and to collect more details about their lifestyle habits, including drug use, sleep quality, and leisure activities. Based on the IPAQ-SF results, we categorized the sample into three groups: light PA (n = 47), moderate PA (n = 29), and vigorous PA (n = 27). Vigorous PA group showed better emotional regulation, lower impulsivity, fewer prefrontal symptoms and unhealthy behaviors, better sleep quality, and more leisure activities. No significant cognitive differences were found. It seems that young people are a vulnerable group with emotional and impulsivity traits and engaging in intense PA appears to be a promising avenue for managing these symptoms. In conclusion, our study suggests that young people are a vulnerable group with emotional and impulsivity traits that may precipitate in future mental disorders. Nevertheless, engaging in PA, particularly at high intensity, appears to be a promising avenue for reducing and managing these symptoms during this critical period of life.

Effects of non-pharmacological interventions for adults with subjective cognitive decline: a network meta-analysis and component network meta-analysis

BACKGROUND

Non-pharmacological interventions have a myriad of available intervention options and contain multiple components. Whether specific components of non-pharmacological interventions or combinations are superior to others remains unclear. The main aim of this study is to compare the effects of different combinations of non-pharmacological interventions and their specific components on health-related outcomes in adults with subjective cognitive decline.

METHODS

PubMed, Embase, Cochrane, CINAHL, PsycINFO, CENTRAL, Web of Science, and China's two largest databases, CNKI and Wanfang, were searched from inception to 22nd, January 2023. Randomized controlled trials using non-pharmacological interventions and reporting health outcomes in adults with subjective cognitive decline were included. Two independent reviewers screened studies, extracted data, and assessed risk of bias. Component network meta-analysis was conducted employing an additive component model for network meta-analysis. This study followed the PRISMA reporting guideline and the PRISMA checklist is presented in Additional file 2.

RESULTS

A total of 39 trials with 2959 patients were included (range of mean ages, 58.79-77.41 years). Resistance exercise might be the optimal intervention for reducing memory complaints in adults with subjective cognitive decline; the surface under the cumulative ranking p score was 0.888, followed by balance exercise (p = 0.859), aerobic exercise (p = 0.832), and cognitive interventions (p = 0.618). Music therapy, cognitive training, transcranial direct current stimulation, mindfulness therapy, and balance exercises might be the most effective intervention components for improving global cognitive function (iSMD, 0.83; 95% CI, 0.36 to 1.29), language (iSMD, 0.31; 95% CI, 0.24 to 0.38), ability to perform activities of daily living (iSMD, 0.55; 95% CI, 0.21 to 0.89), physical health (iSMD, 3.29; 95% CI, 2.57 to 4.00), and anxiety relief (iSMD, 0.71; 95% CI, 0.26 to 1.16), respectively.

CONCLUSIONS

The form of physical activity performed appears to be more beneficial than cognitive interventions in reducing subjective memory complaints for adults with subjective cognitive decline, and this difference was reflected in resistance, aerobic, and balance exercises. Randomized clinical trials with high-quality and large-scale are warranted to validate the findings.

TRIAL REGISTRATION

PROSPERO registry number. CRD42022355363.

Wearable device for continuous sweat lactate monitoring in sports: a narrative review

In sports science, the use of wearable technology has facilitated the development of new approaches for tracking and assessing athletes' performance. This narrative review rigorously explores the evolution and contemporary state of wearable devices specifically engineered for continuously monitoring lactate levels in sweat, an essential biomarker for appraising endurance performance. Lactate threshold tests have traditionally been integral in tailoring training intensity for athletes, but these tests have relied on invasive blood tests that are impractical outside a laboratory setting. The transition to noninvasive, real-time monitoring through wearable technology introduces an innovative approach, facilitating continuous assessment without the constraints inherent in traditional methodologies. We selected 34 products from a pool of 246 articles found through a meticulous search of articles published up to January 2024 in renowned databases: PubMed, Web of Science, and ScienceDirect. We used keywords such as "sweat lactate monitoring," "continuous lactate monitoring," and "wearable devices." The findings underscore the capabilities of noninvasive sweat lactate monitoring technologies to conduct long-term assessments over a broad range of 0-100 mM, providing a safer alternative with minimal infection risks. By enabling real-time evaluations of the lactate threshold (LT) and maximal lactate steady state (MLSS), these technologies offer athletes various device options tailored to their specific sports and preferences. This review explores the mechanisms of currently available lactate monitoring technologies, focusing on electrochemical sensors that have undergone extensive research and show promise for commercialization. These sensors employ amperometric reactions to quantify lactate levels and detect changes resulting from enzymatic activities. In contrast, colorimetric sensors offer a more straightforward and user-friendly approach by displaying lactate concentrations through color alterations. Despite significant advancements, the relationship between sweat lactate and blood lactate levels remains intricate owing to various factors such as environmental conditions and the lag between exercise initiation and sweating. Furthermore, there is a marked gap in research on sweat lactate compared to blood lactate across various sports disciplines. This review highlights the need for further research to address these shortcomings and substantiate the performance of lactate sweat monitoring technologies in a broader spectrum of sports environments. The tremendous potential of these technologies to supplant invasive blood lactate tests and pioneer new avenues for athlete management and performance optimization in real-world settings heralds a promising future for integrating sports science and wearable technology.

Effects of high-intensity interval training on strength, speed, and endurance performance among racket sports players: A systematic review

This study aims to present a critical review of the existing literature on the effects of High-Intensity Interval Training (HIIT) on strength, speed, and endurance performance among racket sports athletes. This study conducted a systematic literature review by PRISMA guidelines. Various well-known academic and scientific databases were used for research collection, including PubMed, EBSCOhost, Scopus, Web of Science, and Google Scholar. Out of 27 relevant studies, 10 were selected for inclusion in this systematic review, all meeting the required inclusion criteria. The quality of each study was assessed using the PEDro scale, with scores ranging from 3 to 5 for the selected studies. HIIT was found to improve racket players' VO2 max (maximum oxygen uptake), running and repetitive sprint performance, jumping performance, and hitting speed during play. Current findings indicate that HIIT can significantly benefit athletic performance. Long-term HIIT allows athletes to enhance their power while improving crucial variables related to both aerobic and anaerobic endurance. This anaerobic endurance and explosive power type is particularly vital for racket sports players. For example, athletes in table tennis and badminton must exert maximum effort during high-intensity middle and back-court play. Racket athletes also need to maintain a stable state while preserving ball speed and positioning, and must quickly recover to prepare for the next rally. This training mechanism can assist athletes in honing their skills and achieving more efficient hitting quality. Therefore, this paper recommends that racket sports athletes incorporate HIIT into their regular training routines. The suggested frequency is three times per week, with each training session lasting 30-40 minutes, and a total duration of six to eight weeks. Trial registration. Systematic Review Registration: [https://inplasy.com/], identififier[INPLASY20230080].

Applied high-intensity interval cardio yoga improves cardiometabolic fitness, energetic contributions, and metabolic flexibility in healthy adults

Purpose: Currently, there is no interventional approach to increase the intensity of Surya Namaskar a popular hatha yoga sequence used worldwide. Therefore, this study investigated how tempo-based high-intensity interval cardio yoga (HIICY) and traditional interval hatha yoga (TIHY) affects cardiometabolic fitness in active adults. Methods: Twenty physically active male and female individuals were randomly separated into HIICY (5 males, 5 females, 1.5 s tempo) and TIHY (5 males, 5 females, 3 s tempo) groups. The intervention included twelve exercise sessions for 4 weeks in both groups. Participants conducted a ramp test to determine their maximal oxygen uptake (V ˙ O2max), maximal velocity at V ˙ O2max (vV ˙ O2max), and maximal heart rate (HRmax). Afterward, they performed a 10-min high-intensity cardio yoga test (HICYT) to determine heart rate (HRpeak and HRmean), oxygen uptake (V ˙ O2peak and V ˙ O2mean), respiratory exchange ratio (RER), blood lactate concentrations (La- peak and ∆La-), fat and carbohydrate oxidations (FATox, CHOox), and energetic contributions (oxidative; W Oxi, glycolytic; W Gly, and phosphagen; W PCr, total energy demand; W Total). Results: V ˙ O2max and vV ˙ O2max showed time and group × time interactions (p < 0.01, p < 0.0001, p < 0.001, respectively). V ˙ O2max after HIICY was significantly higher than in pre-testing and following TIHY (p < 0.001, p < 0.0001, respectively). V ˙ O2peak, V ˙ O2mean, RER, HRpeak, and HRmean during the 10-min HICYT showed significant time effects (p < 0.05). ∆La- indicated a group × time interaction (p < 0.05). Group x time interaction effects for FATox at the fourth and sixth minute were observed (p < 0.05, respectively). Absolute (kJ) and relative (%) W Oxi, W Gly, and W Total showed time and group × time interaction effects (p < 0.05, p < 0.01, respectively). Furthermore, %W Gly was reduced following HIICY (p < 0.05). Additionally, V ˙ O2max and vV ˙ O2max were highly correlated with W Oxi in kJ (r = 0.91, 0.80, respectively). Moderate to high correlations were observed among CHOox, FATox, and absolute V ˙ O2max (r = 0.76, 0.62, respectively). Conclusion: A 4-week period of HIICY improved cardiometabolic fitness, oxidative capacity, and metabolic flexibility compared with TIHY, in physically active adults. Therefore, HIICY is suitable as HY-specific HIIT and time-efficient approach for relatively healthy individuals.

High-intensity interval training attenuates development of autoimmune encephalomyelitis solely by systemic immunomodulation

The impact of high-intensity interval training (HIIT) on the central nervous system (CNS) in autoimmune neuroinflammation is not known. The aim of this study was to determine the direct effects of HIIT on the CNS and development of experimental autoimmune encephalomyelitis (EAE). Healthy mice were subjected to HIIT by treadmill running and the proteolipid protein (PLP) transfer EAE model was utilized. To examine neuroprotection, PLP-reactive lymph-node cells (LNCs) were transferred to HIIT and sedentary (SED) mice. To examine immunomodulation, PLP-reactive LNCs from HIIT and SED donor mice were transferred to naïve recipients and analyzed in vitro. HIIT in recipient mice did not affect the development of EAE following exposure to PLP-reactive LNCs. HIIT mice exhibited enhanced migration of systemic autoimmune cells into the CNS and increased demyelination. In contrast, EAE severity in recipient mice injected with PLP-reactive LNCs from HIIT donor mice was significantly diminished. The latter positive effect was associated with decreased migration of autoimmune cells into the CNS and inhibition of very late antigen (VLA)-4 expression in LNCs. Thus, the beneficial effect of HIIT on EAE development is attributed solely to systemic immunomodulatory effects, likely because of systemic inhibition of autoreactive cell migration and reduced VLA-4 integrin expression.